Fluid actuator with integral mechanical locking means



July 19, 1955 w, DRlSKEL ET AL FLUID ACTUATOR WITH INTEGRAL MECHANICAL LOCKING MEANS Original Filed Aug. 11, 1951 DON M. DR/SKEL P/CHH PDL.HAYP7/QN IN V EN T 0R5.

HTTOE/VE'HSI Patented July 19, 1955 FLUID ACTUATOR WITH INTEGRAL NIECHANI- CAL LOCKING MEANS Don W. Driskel, Glendale, and Richard L. Hayman,

Flintridge, Califi, assignors to Haskel Engineering Associates, Glendale, Calif., a partnership Original application August 11, 1951, Serial No. 241,472. Divided and this application October 26, 1953, Serial No. 388,408

4 Claims. (Cl. 121-40) The present invention relates to improvements in hydraulic or pneumatic actuators and more specifically to means automatically locking an element thereof in an operative position after movement of such element.

The present application constitutes a division of our United States Patent application, Serial Number 241,472, filed August 11, 1951.

Hydraulic or pneumatic actuators of this character include a piston slidably mounted in a cylinder. The piston is moved to difierent operating positions in accordance with fluid, either air, oil, or the like, being applied under pressure to the cylinder. The present invention contemplates the provision of an improved mechanism disposed entirely in the cylinder for locking the piston in one or more of its operating positions. The locking mechanism is automatically released upon application of pneumatic or fluid pressure to the cylinder. More specifically, the present invention contemplates the use of one or more balls for accomplishing this general purpose, and, for that reason, the mechanism is commonly referred to as a ball lock.

One of the important objects of the present invention is to provide an improved hydraulic or pneumatic actuator of this character which incorporates an improved locking mechanism.

A specific object of the present invention is to provide an improved actuator of this character which uses one or more balls for the intended purpose of rigidly locking the piston with respect to the cylinder so as to prevent relative movement between the piston and cylinder.

Another specific object of the present invention is to provide an actuator with an improved locking mechanism therein, such locking mechanism being actuated only when the applied pressure is above a predetermined high threshold value whereby the locking mechanism is prevented from operating spuriously in accordance with, for

example, surges in pressure of the actuating fluid.

Another specific object of the present invention is to provide an actuator of this character which incorporates a novel locking mechanism, the locking mechanism incorporating balls which are moved to and trapped. in diflerent operating positions, using a structure which embodies important features of the present invention.

Another specific object of the present invention, as gleaned from the arrangement shown and described herein, is that the piston may be locked at both of its ends of travel.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

Figures 1, 2, and 3 show a modified structure embodying features of the present invention, Figure 1 being a longitudinal sectional view through a modified actuator;

Figure 2 being a sectional view taken substantially on the line 22 of Figure 1; and Figure 3 being a sectional view taken substantially on the line 33 of Figure 2.

In the arrangement shown in Figures 1, 2, and 3, the piston shown therein is automatically locked at both of its ends of travel. The locking means, however, is automatically unlocked on application of pressure to the piston.

In Figure 1, the piston has mounted thereon a bearing 61 for attachment to, for example, the landing gear of an aircraft, while the cylinder or stationary portion 62 is provided likewise with an apertured portion 63 for suitable attachment to the aircraft.

The piston has a portion of enlarged diameter 64 with an annular recess accommodating the packing ring 65 which cooperates with the internal wall of the cylinder 62. Such enlarged portion 64 is formed with two series of circumferentially disposed semi-hemispherical detents 66, 67. The detents 67 cooperate with the series of balls 68 for locking the piston in its retracted position, while the series of detents 66 cooperate with the series of spaced balls 69 for locking the piston 60 in its extended position. The piston of course is slidably arranged in the cylinder 62, and packing 7t pressed by the stuifing nut 71 provides a fluid-tight seal between the piston and the cylinder.

As shown in Figure 1, the balls 68 are maintained in the detents 67 by the annular ring 72 which is allowed to slide on the stationary apertured sleeve 73. The slidable locking ring 72 is moved to an unlocking position upon application of fluid to the conduit 74 which is in communication with one side of the four circumferentially spaced pistons 75, each of which has its other end vented to the atmosphere. The sleeve 73 is formed with a plurality of radial bores 76 (Figure 2), within which such balls 63 are free to move, it being noted however, that the diameter of each of the balls is greater than the wall thickness of the sleeve 73.

The retaining ring 72 is normally biased in the position shown in Figure 3 by eight spaced coil compression springs 77, recessed in a bore in the casing end 78. It is observed that the locking ring 72 is provided with an annular arcuate cam face or surface 79 which serves, in operation of the device, to cam the series of balls 68 radially inwardly into locking position. The stationary cylinder comprises essentially three parts; namely, the aforementioned casing end 78, the barrel 80, and the end casing 81.

The barrel 80 is externally threaded at each end and mounts cooperating threaded collars 82, 83 thereon. Such threaded collars are each internally and externally grooved for annular 0 rings 34, 85, 36, 87 for providing fluid-tight seals, both internally and externally. The casing ends 78 and 81 are each internally threaded and have mounted thereon, the corresponding locking nuts 88, 89 which contact the collars 82, 83. These collars 82, 83 likewise contact the sleeves 73 and 90, the sleeve 99 being of identical construction as the sleeve 73 and serving to retain the balls 69 in the same manner as the balls 68 are retained.

A sleeve 91 with oppositely turned flanges on opposite ends thereof is slidably mounted Within the sleeve 73. Likewise the sleeve 92 of identical construction as sleeve 91 is slidable internally of the sleeve 99 for a similar purpose, A pre-stressed coil compression spring 93 has one of its ends engaging the internal flange of sleeve 91 and the other one of its ends contacting the casing 78 so that such sleeve 91 is biased to the left in Figure 1. Likewise, a spring 94 identical with the spring 93 is disposed at the other end and cooperates in like manner with the sleeve 92. In general, the purpose of the sleeves 91 and 92 is to prevent the series of balls 68 or 69, as the case piston portion 64.

the right-hand end of the actuator in Figure 1 is identical with the locking mechanism at the left-hand end of the actuator. Thus, the locking ring 95 is identical in structure with the locking ring 72 and serves the same purposes. The locking ring'95 has associated therewith a plurality of fluid actuated pistons 96 connected to the ring '95 in the same manner as are the pistons 75 connected to the ring 72. However, while the pistons 75 have one of their ends vented to the atmosphere, the pistons 96 also have one of their ends vented to the atmos phere, but in addition, are attached to the'ring 97 to which is connected an actuating element 98 for the micr oswitch 99.

Likewise, the conduit 74 for introducing fluid under pressure to the pistons 75 has its counterpart in the conduit 100 Whichis in communication with the pistons 96. It is observed that conduit 74 (and likewise the conduit 100) is in communication not only with the corresponding pistons 75 and-96, but as observed with reference to .Figure 3, is in communication with corresponding opposite sides of the enlarged piston portion 64.

Specifically, in Figure 3, the conduit 74 is in communication with the annular space 101, which in turn, is in communication through the series of bores 102 and radially extending bore 103 with one side of the enlarged A similar fluid path (not shown) places conduit 100 in communication with the opposite side of the enlarged piston portion 64.

In operation of the arrangement shown in Figure 1 (assuming that the piston is in its retracted and locked position as shown in Figure 1), the piston is unlocked and moved to the left upon application of fluid under pressure to the conduit 74. In such case, the fluid acts on the four pistons 75 to cause them to move to the right carrying with them the annular locking ring 72; simultaneously, fluid under pressure is delivered through conduits 101, 102, and 103 to the right-hand side of theenlarged piston portion 64, The resulting movement of the locking ring 72 to the right in Figure '1 allows the eight'balls 68 to move radially outwardly, thus freeing the piston for movement under the influence of pressure thus applied thereto through conduits 101, 102, and 103.

During initial movement of the piston portion 64, the

spring pressed sleeve 91 follows such movement and covers the radial bores within which balls 68 tend to' move radially inwardly. The sleeve 91-thus serves essentially as a ball retaining ring. .The piston portion 64-thus continues to move to the left in Figure l, and it engages the sleeve 92, which at that time acts as a retaining ring V for the series of balls 69.

Continued further movement of the piston portion 64-results in the compression of the spring 94 and movement of the sleeve 92 until the grooves 66 are in substantial registry with the balls 69. balls 69 are pressed radially inwardly into such detents 66 by the spring pressed locking ring 95 which has an arcuate cam surface 104 thereon for that purpose. As a matter of fact, the slidable locking ring 95 overrides the series of balls 69 and ultimately serves as a retaining ring for the series of balls 69, preventing their radial outward movement. In other, words, the ring 95 ultimately assumes the position with respect to ball 69 as shown with respect to ball 68 and ring 72 in Figure 1. Thus, the enlarged piston portion 64 is locked in the fully extended position of the piston. Thereafter, to unlock the piston portion 6 4 and to move the same to the right in Figure 1, necessitates the application of fluid In such case the pressure to conduit 100. In such case, the balls 69 are released as described above in connection with ball 68 and the piston portion 64 moves to the right until the condition shown in Figure 1 exists.

The aforementioned microswitch 99 may be used for different purposes in controlling solenoid valves and supplying fluid under pressure to the conduits 74 and 100. For'example, the microswitch 99 may serve to' interrupt the application of pressure to conduit 74 when the piston has been moved to its most extended and locked position or for indicationpurposes.

While the particular embodiments of the present invention have been shown and described, it will be obvious to' those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and 1 modifications as fall within the true spirit and scope of this invention.

We claim:

1. In an arrangement of the character described, a fluid pressure cylinder, a piston slidably mounted in said cylinder and having a plurality of circumferentially arranged reentrant portions therein, a plurality of balls circumferentially disposed around said piston and engageable with a corresponding one of said reentrant portions, means mounted on said cylinder and circumferentially disposed around said balls and having a cam sur-' face thereon engageable with said balls for moving said balls radially inwardly with respect to the axis of said piston to thereby lock the piston to said cylinder, spring means constantly acting, when said balls are'in piston locking position tending to allow movement of said balls radially outwardly out of locking position, and fluid pressure operated means for moving said circumferentially arranged means to allow said balls to move radially outwardly under the influence of said spring means.

2. In an arrangement of the character described, a fluid pressure cylinder, a piston slidably mounted in said cylinder, a plurality of locking balls circumferentially arranged. with respect to said piston near each end of said cylinder, said piston having a first series and a second series of reentrant portions spaced longitudinally v of such piston and engageable with corresponding balls for locking said piston with respect to said cylinder in both an extended and a retracted position of said piston, fluid pressure means circumferentially arranged around said piston and slidably mounted on said;cylinder near.

each end of said cylinder for moving a corresponding series of said balls relative to corresponding reentrant portions of said piston.

3. The arrangement set forth 'in claim 2 in which the 7 last mentioned means comprises sleeves mounted on the cylinder 'which are circumferentially disposed around corresponding balls with a cam surface on said sleeves for engaging and moving said balls.

4. The arrangement set forth in claim'2 in which a pair of sleeves are slidably mounted internally of said cylinder near opposite ends thereof, such sleeves having 1 a diameter substantially equal to the diameter of the piston, spring means acting between said cylinder and corresponding sleeves for moving the corresponding sleeve to a position within corresponding circumferen tially arranged locking balls to thereby maintain said balls within said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 

